This invention relates to an electromotive machine, and more particularly to a stator winding for an axial air gap generator.
While the typical electric motor or generator in common use is a type referred to as a radial air gap device, axial air gap devices are also well known. In a radial air gap device, a cylindrical rotor turns within an outer cylindrical stator, whereas an axial air gap device includes a generally flat "pancake" stator and, coaxial with it, at least one generally flat "pancake" rotor. The T. S. Varga U.S. Pat. No. 4,959,578, for example, describes a motor of the axial gap type.
An axial gap permanent magnet (PM) generator has advantages making it useful in aircraft electric power generating systems because it is relatively light, short and efficient. A preferred arrangement is one including a stator having windings and laminated stator teeth, and a PM rotor on each side of the stator.
Such an arrangement presents construction problems, however. The only practical way to support the stator is by attachment to the end turns at the outer diameter of the stator windings. Since a rotor is on each side of the stator, no "back iron" is provided in the stator, and therefore the stator teeth must be supported by other means. Further, the stator windings must be mounted in a relatively tight space, particularly at the inner diameter of the stator. At the outer diameter of the stator, the end turns of a conventional winding can be long and bulky, resulting in higher copper losses (and heat) and an undesirable increase in the overall diameter of the stator.
It is a primary object of the present invention to provide an improved construction which avoids the foregoing problems.